1. Field of the Invention
The present invention relates to a method for regulating a gas turbine apparatus in part load operation.
2. Discussion of Background
It has become known to effect the partial load during operation of gas turbine groups via a reduction in the fuel quantity in which the inlet temperature at the turbine is lowered by such a reduction while maintaining the combustion air. This simple provision per se of a partial-load operation proves to be too unattractive with regard to the efficiency, since the efficiency falls almost in proportion to the power reduction. In the attempt to keep this relatively high efficiency loss within narrower limits, it has already been proposed, for example, to additionally assist the lowering of the load by an adjustment of the compressor guide blades.
However, in a gas-turbine group having sequential combustion, in which the hot gases prepared in a first combustion chamber act upon a first turbine, the exhaust gases flowing out of the latter are again processed in a second combustion chamber to form hot gases which then act upon a second turbine, the requirements for providing a partial-load operation at maximized efficiency by the methods which have been disclosed can no longer be met, all the more if the second combustion chamber is designed for self-ignition, i.e. if the temperature of the exhaust gases from the first turbine has to make possible self-ignition in connection with the fuel injected there.
In such a gas-turbine group, but not only in such a gas-turbine group, the output could certainly be lowered by closing the inlet guide row of the compressor. But this would inevitably necessitate a reduction in the injected fuel quantity to the two combustion chambers of the gas-turbine group. Now if the second combustion chamber is designed for self-ignition, the fuel quantities cannot be reduced simultaneously at both combustion chambers, for the temperature of the exhaust gases from the first turbine could then no longer be maintained for the subsequent self-ignition in the second combustion chamber.